Single-tank packed bed heat storage system based on four-way valve switching and heat supplement

Abstract

The application relates to the technical field of thermal energy storage, and discloses a single-tank packed bed heat storage system based on four-way valve switching and heat supplement, which comprises a packed bed, a four-way valve, a power unit, a heater, a cold-end heat exchanger and a connecting pipeline. The four-way valve is used as a flow direction control core, and by controlling the power-on state of the four-way valve, the flow direction of the heat transfer fluid in the system can be conveniently switched, so that the conversion between the heat storage mode and the heat release mode is realized. The heater and the cold-end heat exchanger are arranged in series on the same main pipeline between the heat exchange circulating interface of the four-way valve and the power unit, so that when the heat release mode is switched to the heat storage mode, the path of the heat transfer fluid is consistent, the influence of thermal inertia is reduced, and the stability of the temperature gradient layer is ensured. The heater is arranged at the front end of the fluid inlet of the cold-end heat exchanger, can start the heater to accurately supplement the heat of the heat transfer fluid at the end of the heat release mode, so that the temperature of the fluid entering the cold-end heat exchanger is improved, and the quality and stability of the output heat energy are ensured.

Description

Technical Field

[0001] This application relates to the field of thermal energy storage technology, and in particular to a single-tank filled bed thermal energy storage system based on four-way valve reversing and reheating. Background Technology

[0002] As the global energy structure transitions towards a green and low-carbon model, efficient and economical energy storage technologies have become crucial for addressing the intermittency and instability of renewable energy sources. Among these, thermal energy storage technology, with its advantages of large capacity, low cost, and long lifespan, shows broad application prospects in solar power generation, thermal power generation, industrial waste heat recovery, and district heating. Of various thermal energy storage technologies, single-tank packed bed inclined temperature layer thermal energy storage technology is considered one of the most commercially viable solutions due to its small footprint, simple structure, low investment cost, and flexible operation. However, this technology still faces several key technical challenges in its engineering application. The first is the issue of system complexity and reliability. To achieve the switching between heat storage and heat release processes, the flow direction of the heat transfer fluid in the packed bed must be changed. When molten salt is used as the heat transfer medium, traditional solutions typically employ two sets of pump-valve systems or a combination of four shut-off valves to achieve this switching. This design not only increases the initial investment and complexity of the system but also introduces a large number of pipe connections and flange interfaces, leading to significant heat loss. Most importantly, in heat release mode, the heat storage pipeline is stagnant, and the molten salt within it is highly susceptible to solidification due to temperature drops. Continuous electric heating is necessary, significantly increasing operating energy consumption and maintenance costs. While using air as the heat transfer medium avoids fluid solidification, its low volumetric heat capacity and high thermal inertia present another challenge: during the switch from heat release to heat storage, the low-temperature air must pass through a large heater and corresponding pipelines to enter the bed, resulting in the inlet temperature of the packed bed being lower than the top temperature for an extended period during the initial heat storage phase, severely damaging the established temperature gradient layer. Secondly, there is the issue of temperature gradient layer degradation itself. During long-term circulation, due to factors such as axial heat diffusion, insufficient solid-liquid heat exchange, and inlet / outlet effects, the temperature gradient layer gradually thickens and disperses, leading to a decrease in usable heat storage capacity, unstable outlet temperature, and a decline in system efficiency. To address this problem, existing technologies often employ a cutoff temperature control method (e.g., terminating operation when the heat release outlet temperature falls below a preset threshold) coupled with dynamic flow regulation to curb axial diffusion of the temperature gradient layer. However, the effectiveness of this method is highly dependent on accurate temperature monitoring and rapid system response, and it still needs to be combined with an optimized system structure to achieve long-term stability of the thermocline.

[0003] In summary, existing single-tank packed bed inclined layer thermal storage systems have the following technical problems:

[0004] 1. The system has a complex structure and a cumbersome reversal process, relying on a multi-pump and multi-valve configuration, which leads to high equipment costs, many possible failure points, and reduced system reliability;

[0005] 2. The complex piping system with numerous connection points leads to significant heat loss and low operating efficiency;

[0006] 3. For molten salt heat transfer media, idle pipelines need to be continuously electrically heated to prevent solidification, which significantly increases operating energy consumption and costs;

[0007] 4. During mode switching, the large thermal inertia of the heater, heat exchanger and pipelines leads to a slow response in the inlet temperature, which can easily disrupt the stability of the established temperature gradient.

[0008] 5. At the end of the heat release phase, when the thermocline moves to the outlet, the outlet temperature and thermal energy quality decrease, affecting the efficient utilization of thermal energy.

[0009] Therefore, it is crucial to develop a single-tank packed bed thermal storage system that is structurally simple, reliable in operation, has low heat loss, and can effectively maintain the stability of the thermocline. Utility Model Content

[0010] The purpose of this application is to provide a single-tank filled bed thermal storage system based on four-way valve switching and heat replenishment. It uses a single four-way valve as the core component for flow direction control. By controlling its energization state, the heat storage and heat release modes can be easily switched, replacing the traditional complex valve group arrangement, greatly simplifying the pipeline system, and reducing leakage points and heat loss.

[0011] The embodiments of this application disclose a single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment, including: a packed bed, a four-way valve, a power unit, a heater and a cold end heat exchanger connected and fluidly communicated by connecting pipelines;

[0012] The packed bed is filled with solid thermal storage material for storing thermal energy;

[0013] The power unit is used to provide power for the fluid circulation within the system;

[0014] The heater is used to heat the heat transfer fluid in heat storage mode;

[0015] The cold-end heat exchanger is used to extract heat from the heat transfer fluid in heat release mode and heat the working fluid on the user side.

[0016] The four-way valve has four interfaces: a power unit interface, a bottom interface of the packed bed, a heat exchange circulation interface, and a top interface of the packed bed.

[0017] The top port of the packed bed is connected to the first end of the heater, the second end of the heater is connected to the first end of the cold end heat exchanger, the second end of the cold end heat exchanger is connected to the top port of the packed bed of the four-way valve, the bottom port of the packed bed is connected to the bottom port of the packed bed of the four-way valve, the outlet of the power unit is connected to the power unit port of the four-way valve, and the inlet of the power unit is connected to the heat exchange circulation port of the four-way valve.

[0018] The four-way valve has a movable cover slider inside. By moving the cover slider, the flow path connection state in the system can be changed, thereby allowing the system to switch between the heat storage mode and the heat release mode.

[0019] In another preferred embodiment, the power unit interface is located on the first side of the four-way valve; the bottom interface of the packed bed, the heat exchange circulation interface, and the top interface of the packed bed are located on the second side of the four-way valve and arranged in a left-to-right order.

[0020] In another preferred embodiment, the four-way valve is an electromagnetically driven four-way directional valve.

[0021] In another preferred embodiment, when the four-way valve is de-energized, the cover slider moves to the left under the action of the spring, covering the bottom interface of the packed bed and the heat exchange circulation interface, so that the flow path from the power unit interface to the top interface of the packed bed and the flow path from the bottom interface of the packed bed to the heat exchange circulation interface are connected, and the system enters the heat storage mode.

[0022] In another preferred embodiment, in the heat storage mode, the flow path of the heat transfer fluid is:

[0023] Bottom port of packed bed → Bottom interface of packed bed → Heat exchange circulation interface → Inlet of power unit → Outlet of power unit → Power unit interface → Top interface of packed bed → Cold end heat exchanger → Heater → Top port of packed bed → Bottom port of packed bed, completing the cycle;

[0024] In the heat storage mode, the inclined temperature layer moves from top to bottom within the packed bed.

[0025] In another preferred embodiment, in the heat storage mode, the heater heats the heat transfer fluid, the user side of the cold-end heat exchanger has no working fluid, and the cold-end heat exchanger does not exchange heat.

[0026] In another preferred embodiment, when the four-way valve is energized, the covering slider moves to the right under the action of electromagnetic force, covering the heat exchange circulation interface and the top interface of the packed bed, so that the flow path from the power unit interface P to the bottom interface B of the packed bed and the flow path from the top interface T of the packed bed to the heat exchange circulation interface E are connected, and the system enters the heat release mode.

[0027] In another preferred embodiment, under the heat release mode, the flow path of the heat transfer fluid is:

[0028] The cycle is as follows: Power unit outlet → Power unit interface → Bottom interface of packed bed → Bottom port of packed bed → Top port of packed bed → Heater → Cold end heat exchanger → Top interface of packed bed → Heat exchange circulation interface → Inlet of power unit → Outlet of power unit, thus completing the cycle.

[0029] In the heat release mode, the inclined temperature layer moves from bottom to top within the packed bed.

[0030] In another preferred embodiment, in the heat release mode, the heater does not heat the heat transfer fluid, and the cold-end heat exchanger transfers heat to the user-side working fluid.

[0031] In another preferred embodiment, the heater is further configured to provide auxiliary heating to the heat transfer fluid that is about to enter the cold-end heat exchanger and whose temperature has dropped to a preset threshold at the end of the operation of the heat release mode.

[0032] The main differences and effects of the implementation method of this application compared with the prior art are as follows:

[0033] This application discloses a single-tank filled bed thermal storage system based on a four-way valve for reversing and reheating. It uses a single four-way valve as the core component for flow control. By controlling its energization state, the heat storage and heat release modes can be easily switched, replacing the traditional complex valve group arrangement, greatly simplifying the pipeline system, and reducing leakage points and heat loss.

[0034] Furthermore, by integrating the heater and the cold-end heat exchanger onto the same main pipeline, the fluid path is optimized, significantly reducing the thermal inertia effect during mode switching, enabling the inlet temperature to quickly reach the set value, which is beneficial for the formation and stability of the thermocline.

[0035] Furthermore, a heater supplementary heating strategy is introduced at the end of the heat release mode to ensure the quality and stability of the output heat energy and extend the effective heat release time.

[0036] Furthermore, by using the switching action of the four-way valve in conjunction with the start-stop control of the heater, the system achieves efficient, stable, and flexible operation.

[0037] Furthermore, replacing multiple pump valves with a single four-way valve greatly simplifies the system structure and pipeline connections, reduces potential leakage points, lowers equipment costs and failure rates, and improves system operational reliability.

[0038] Furthermore, the simplified piping system significantly reduces heat dissipation area and heat loss, which helps improve the overall energy efficiency of the system.

[0039] Furthermore, for molten salt systems, there are no idle or stagnant pipelines after the reversal (mode switching), which fundamentally avoids the risk of molten salt solidifying in non-operating pipelines, reduces or even eliminates the dependence on continuous electric heating, and saves operating costs.

[0040] Furthermore, by introducing a heater to supplement heat under certain special operating conditions or at the end of heat release, the drop in outlet temperature can be effectively compensated, ensuring that the quality of the output heat energy meets the requirements of the user side (such as steam generator), thereby improving the availability of heat energy and system efficiency. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a single-tank packed bed thermal storage system based on a four-way valve switching and heat replenishment according to an embodiment of this application, showing the flow path of the heat transfer fluid in thermal storage mode.

[0042] Figure 2 This is a schematic diagram of the connection structure of the four-way valve interface in heat storage mode.

[0043] Figure 3 This is a schematic diagram of a single-tank packed bed thermal storage system based on a four-way valve switching and heat replenishment according to an embodiment of this application, showing the flow path of the heat transfer fluid in the heat release mode.

[0044] Figure 4 This is a schematic diagram of the connection structure of the four-way valve interface in heat release mode. Detailed Implementation

[0045] In the following description, numerous technical details are presented to facilitate the reader's understanding of this application. However, those skilled in the art will understand that the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0046] First, it should be noted that, unless otherwise defined, the technical terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this utility application pertains. The terms "top," "bottom," "left," "middle," "right," "upper," "lower," and other terms indicating orientation used in the embodiments of the application are only used to describe the exemplary relative positional relationships shown in the figures for ease of understanding and are not intended to limit the scope of protection of this application.

[0047] Explanation of some concepts:

[0048] A single-tank packed bed thermal energy storage system refers to a system that uses solid filling material as the thermal storage medium and forms and maintains a "temperature gradient layer" with a temperature gradient through the flow of heat transfer fluid, thereby realizing the storage and release of thermal energy.

[0049] The temperature gradient layer refers to the temperature gradient distribution area along the depth of the bed in a single-tank packed bed thermal storage system.

[0050] Additionally, it should be noted that in this paper, single-tank filled bed thermal storage system and single-tank filled bed inclined temperature layer thermal storage system refer to the same concept, heat transfer medium and heat transfer fluid refer to the same concept, switching and conversion refer to the same concept, and user side and cold side, cold end refer to the same concept.

[0051] This application aims to address the problems of complex structure, large heat loss, high heat tracing cost, and thermal inertia-induced degradation of the thermocline stability during mode switching in existing single-tank packed bed thermal storage systems due to the use of multiple pumps and valves.

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0053] The embodiments of this application relate to a single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment. Figure 1 and Figure 3 This is a schematic diagram of the structure of the single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment.

[0054] Specifically, such as Figure 1 and Figure 3 As shown, the single-tank packed bed thermal storage system based on four-way valve reversing and reheating includes: a packed bed 1 connected and in fluid communication via a connecting pipe 6, a four-way valve 2, a power unit 3, a heater 4, and a cold-end heat exchanger 5.

[0055] The packed bed 1 is filled with solid thermal storage material for storing thermal energy.

[0056] In this embodiment, the solid thermal storage material is preferably rock, ceramic spheres, etc.

[0057] The power unit 3 is used to provide power for the fluid circulation within the system.

[0058] The power unit 3 varies depending on the heat transfer medium, which can be air, molten salt, etc.

[0059] In this embodiment, the heat transfer medium is preferably molten salt, and correspondingly, the power unit 3 is preferably a molten salt pump.

[0060] Furthermore, preferably, the power unit 3 adopts frequency conversion control in order to adjust the flow rate in different modes, optimize the heat exchange process, and save energy consumption.

[0061] The heater 4 is used to heat the heat transfer fluid in heat storage mode.

[0062] In this embodiment, the heater 4 is preferably an electric heater, a molten salt furnace, or the like.

[0063] The cold-end heat exchanger 5 is used to extract heat from the heat transfer fluid in heat release mode and heat the user-side working fluid. For example, the user-side working fluid can be water, and the cold-end heat exchanger 5 is used to heat the water to generate steam.

[0064] The four-way valve 2 has four interfaces: power unit interface P, bottom interface B of the packed bed, heat exchange circulation interface E, and top interface T of the packed bed.

[0065] Figure 2 and Figure 4 This is a schematic diagram of a preferred four-way valve, wherein... Figure 2 The connection structure of the four-way valve interface is shown in heat storage mode; Figure 4 The connection structure of the four-way valve interface is shown in heat release mode.

[0066] Specifically, such as Figure 2 and Figure 4 As shown, in this preferred four-way valve, the power unit interface P is located on the first side of the four-way valve 2; the bottom interface B of the packed bed, the heat exchange circulation interface E, and the top interface T of the packed bed are located on the second side of the four-way valve 2, and are arranged in order from left to right.

[0067] For example Figure 1 and Figure 3As shown, the top port of the packed bed 1 is connected to the first end of the heater 4, the second end of the heater 4 is connected to the first end of the cold end heat exchanger 5, the second end of the cold end heat exchanger 5 is connected to the top port T of the packed bed of the four-way valve 2, the bottom port of the packed bed 1 is connected to the bottom port B of the packed bed of the four-way valve 2, the outlet of the power unit 3 is connected to the power unit port P of the four-way valve 2, and the inlet of the power unit 3 is connected to the heat exchange circulation port E of the four-way valve 2.

[0068] like Figure 2 and Figure 4 As shown, the four-way valve 2 has a movable cover slider 21 inside. By moving the cover slider 21, the flow path connection state in the system can be changed, thereby allowing the system to switch between the heat storage mode and the heat release mode.

[0069] By controlling the position of the slider inside the four-way valve, the flow direction of the fluid in this single-tank packed bed thermal storage system can be easily switched, thereby realizing the conversion between heat storage mode and heat release mode, replacing the traditional complex system with multiple pumps and multiple valves.

[0070] In this embodiment, preferably, the four-way valve 2 is an electromagnetically driven four-way directional valve, which has a fast response speed and precise control.

[0071] By controlling the left and right movement of the sliding block 21 inside the four-way valve 2 through power-on or power-off, the flow path connectivity state within the single-tank filled bed thermal storage system is changed.

[0072] Specifically, such as Figure 2 As shown, when the four-way valve 2 is de-energized, the covering slider 21 moves to the left under the action of the spring 22, covering the bottom interface B of the packed bed and the heat exchange circulation interface E, so that the flow path from the power unit interface P to the top interface T of the packed bed and the flow path from the bottom interface B of the packed bed to the heat exchange circulation interface E are connected, and the system enters the heat storage mode.

[0073] In other words, when the heat storage mode is activated, the four-way valve 2 is de-energized, and the cover slider 21 inside the four-way valve 2 moves to the left under the action of the spring 22, covering the bottom interface B of the packed bed and the heat exchange circulation interface E, blocking the flow path P→B and the flow path P→E, thereby making the right end flow path P→T of the four-way valve 2 and the middle flow path B→E of the four-way valve 2 unobstructed.

[0074] It should be noted that in this article and the accompanying figures, "→" indicates the direction of fluid flow within the system.

[0075] It should be noted that when the covering slider 21 covers the bottom interface B of the packed bed and the heat exchange circulation interface E, the flow paths between the bottom interface B and the heat exchange circulation interface E are connected, but other flow paths of the bottom interface B and the heat exchange circulation interface E are blocked. Specifically, the other flow paths of the bottom interface B refer to the flow paths between the bottom interface B and the power unit interface P, and between the bottom interface B and the top interface T of the packed bed; the other flow paths of the heat exchange circulation interface E refer to the flow paths between the heat exchange circulation interface E and the power unit interface P, and between the heat exchange circulation interface E and the top interface T of the packed bed.

[0076] like Figure 1 As shown, in the heat storage mode, the flow path of the heat transfer fluid in the single-tank packed bed heat storage system is as follows:

[0077] Bottom port of packed bed 1 → Bottom interface B of packed bed → Heat exchange circulation interface E → Inlet of power unit 3 → Outlet of power unit 3 → Power unit interface P → Top interface T of packed bed → Cold end heat exchanger 5 → Heater 4 → Top port of packed bed 1 → Bottom port of packed bed 1, completing the cycle.

[0078] In the heat storage mode, the inclined temperature layer moves from top to bottom within the packed bed 1.

[0079] In the heat storage mode, the heater 4 heats the heat transfer fluid, the user side of the cold end heat exchanger 5 has no working fluid, and the cold end heat exchanger 5 does not exchange heat.

[0080] In other words, in the heat storage mode, the heater 4 is working, and the cold end heat exchanger 5 is not working.

[0081] For example Figure 4 As shown, when the four-way valve 2 is energized, the covering slider 21 moves to the right under the action of electromagnetic force, covering the heat exchange circulation interface E and the top interface T of the packed bed, so that the flow path from the power unit interface P to the bottom interface B of the packed bed and the flow path from the top interface T of the packed bed to the heat exchange circulation interface E are connected, and the system enters the heat release mode.

[0082] In other words, when the heat release mode is activated, the four-way valve 2 is energized, and the cover slider 21 inside the four-way valve 2 moves to the right under the action of electromagnetic force, covering the heat exchange circulation interface E and the top interface T of the packed bed, blocking the flow paths P→E, P→T, B→E and B→T, thereby making the left end flow path P→B of the four-way valve 2 and the middle flow path T→E of the four-way valve 2 unobstructed.

[0083] It should be noted that when the covering slider 21 covers the heat exchange circulation interface E and the top interface T of the packed bed, the flow paths between the heat exchange circulation interface E and the top interface T of the packed bed are connected, but other flow paths of the heat exchange circulation interface E and the top interface T of the packed bed are blocked. Specifically, the other flow paths of the heat exchange circulation interface E refer to the flow paths between the heat exchange circulation interface E and the power unit interface P, and between the heat exchange circulation interface E and the bottom interface B of the packed bed; the other flow paths of the top interface T of the packed bed refer to the flow paths between the top interface T of the packed bed and the power unit interface P, and between the top interface T of the packed bed and the bottom interface B of the packed bed.

[0084] like Figure 3 As shown, in the heat release mode, the flow path of the heat transfer fluid is:

[0085] The cycle is completed as follows: outlet of power unit 3 → power unit interface P → bottom interface B of packed bed → bottom port of packed bed 1 → top port of packed bed 1 → heater 4 → cold end heat exchanger 5 → top interface T of packed bed → heat exchange circulation interface E → inlet of power unit 3 → outlet of power unit 3.

[0086] In the heat release mode, the inclined temperature layer moves from bottom to top in the packed bed 1, and the heat transfer fluid flows from bottom to top through the packed bed and is heated by the heat storage material.

[0087] In the heat release mode, the heater 4 does not heat the heat transfer fluid, and the cold-end heat exchanger 5 extracts heat from the heated heat transfer fluid and transfers the heat to the user-side working fluid.

[0088] In other words, in the heat release mode, especially in the initial and middle stages of the heat release mode, the heater 4 does not work, while the cold end heat exchanger 5 works.

[0089] The connecting pipe 6 is used to connect the various components of the single-tank filled bed thermal storage system to form a circulation loop.

[0090] In this embodiment, preferably, all high-temperature pipelines should be covered with insulation layers to further reduce heat loss.

[0091] Furthermore, preferably, in this embodiment, the heater 4 is also used to provide auxiliary heating to the heat transfer fluid that is about to enter the cold end heat exchanger 5 and whose temperature has been reduced to a preset threshold at the end of the operation of the heat release mode.

[0092] At the end of the heat release mode operation, when the temperature at the outlet of the packed bed 1 (i.e. the top port of the packed bed 1) drops to a preset threshold (e.g., close to but higher than the minimum temperature required by the user), the energized state of the four-way valve 2 and the main circulation path remain unchanged.

[0093] The heater 4 is activated to provide auxiliary heating for the heat transfer fluid, which has already cooled down, before it enters the cold end heat exchanger 5.

[0094] The heat transfer fluid, after being reheated, enters the cold-end heat exchanger 5, which can provide stable heat to the user side that meets the quality requirements.

[0095] Using the heater 4, the heat transfer fluid is auxiliaryly heated at the end of the heat release mode operation, which can effectively ensure the user's heat demand and ensure the output quality of heat energy even under certain extreme conditions.

[0096] Furthermore, preferably, the power of the heater 4 is adjustable so as to provide precise and on-demand heating according to changes in the outlet temperature, thereby avoiding energy waste.

[0097] As described above, the operation mode of this single-tank filled bed thermal storage system based on four-way valve reversing and heat replenishment is achieved by controlling the on / off state of the four-way valve 2 and the start / stop of the heater 4, specifically including heat storage mode and heat release mode (including end-stage heat replenishment mode). First, using the four-way valve as the core of flow direction control, the flow direction of the fluid within the single-tank filled bed thermal storage system can be easily switched by controlling the position of the sliding block inside the four-way valve, thereby realizing the conversion between heat storage mode and heat release mode, replacing the traditional complex system with multiple pumps and valves. Furthermore, the heater 4 and the cold-end heat exchanger 5 are arranged in the same pipeline, connected in series on the same main pipeline between the heat exchange circulation interface E of the four-way valve 2 and the power unit 3. This ensures that the fluid flows along the same path when switching from heat release mode to heat storage mode, optimizing the fluid path and significantly reducing the temperature response delay caused by the thermal inertia of the equipment and pipelines, which is beneficial for maintaining the stability of the thermocline. Furthermore, the electric heater 4 is positioned at the fluid inlet of the cold-end heat exchanger 5. This arrangement allows for precise reheating of the heat transfer fluid during the final stages of the heat release mode, when the temperature gradient layer moves to the bottom of the packed bed, causing a drop in outlet temperature. This increases the temperature of the fluid entering the cold-end heat exchanger 5, ensuring the quality and stability of the output heat energy and extending the effective heat release time. Through the switching action of the four-way valve, combined with the start / stop control of the heater, efficient, stable, and flexible system operation is achieved.

[0098] Compared with existing technologies, this single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment has the following significant advantages:

[0099] 1. Simplified system and high reliability: The use of a four-way valve to replace multiple pump valves greatly simplifies the system structure and pipeline connection, reduces potential leakage points, lowers equipment costs and failure rate, and improves the reliability of system operation.

[0100] 2. Reduced heat loss and improved energy efficiency: The simplified piping system significantly reduces heat dissipation area and heat loss, which helps to improve the overall energy efficiency of the system.

[0101] 3. Avoid molten salt solidification and reduce heat tracing requirements: For molten salt systems, there are no idle or stagnant pipelines after reversal, which fundamentally avoids the risk of molten salt solidifying in non-operating pipelines, reduces or even eliminates the dependence on continuous electric heat tracing, and saves operating costs.

[0102] 4. Suppressing thermal inertia and stabilizing the tundra: The heater and heat exchanger are arranged in the same pipeline, which optimizes the fluid path and effectively suppresses the influence of thermal inertia during mode switching, so that the inlet temperature can quickly reach the set value, which is conducive to the formation and stabilization of the tundra.

[0103] 5. Thermal Energy Quality Assurance: By introducing a heater to supplement heat under certain special operating conditions or at the end of heat release, the drop in outlet temperature can be effectively compensated, ensuring that the quality of output thermal energy meets the requirements of the user side (such as steam generator), thereby improving the availability of thermal energy and system efficiency.

[0104] In summary, this single-tank filled bed thermal storage system based on four-way valve reversing and heat replenishment has a compact structure, simple reversing operation, can effectively reduce heat loss, suppress the influence of thermal inertia, maintain the stability of the thermocline, and improve the overall performance of the system. It is particularly suitable for large-scale thermal storage scenarios such as solar energy, thermal power generation, district heating, and industrial waste heat recovery.

[0105] It should be noted that the components or devices mentioned in the embodiments of this application are all logical modules. Physically, a logical module can be a physical module, a part of a physical module, or a combination of multiple physical modules. The physical implementation of these logical modules themselves is not the most important factor; rather, the combination of functions implemented by these logical modules is the key to solving the technical problem proposed in this application. Furthermore, to highlight the innovative aspects of this application, the above-described system embodiments have not introduced components or devices that are not closely related to solving the technical problem proposed in this application. This does not mean that other components or devices do not exist in the above embodiments.

[0106] It should be noted that in the claims and specification of this patent, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0107] Although this application has been illustrated and described with reference to certain preferred embodiments thereof, those skilled in the art should understand that various changes in form and detail may be made thereto without departing from the spirit and scope of this application.

Claims

1. A single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment, characterized in that, include: The packed bed (1), four-way valve (2), power unit (3), heater (4) and cold end heat exchanger (5) are connected and fluidly communicated by connecting pipe (6); The packed bed (1) is filled with solid thermal storage material for storing thermal energy; The power unit (3) is used to provide power for the fluid circulation within the system; The heater (4) is used to heat the heat transfer fluid in heat storage mode; The cold-end heat exchanger (5) is used to extract heat from the heat transfer fluid in heat release mode and heat the working fluid on the user side. The four-way valve (2) has four ports: power unit port (P), bottom port of packed bed (B), heat exchange circulation port (E), and top port of packed bed (T); The top port of the packed bed (1) is connected to the first end of the heater (4), the second end of the heater (4) is connected to the first end of the cold end heat exchanger (5), the second end of the cold end heat exchanger (5) is connected to the top port (T) of the packed bed of the four-way valve (2), the bottom port of the packed bed (1) is connected to the bottom port (B) of the packed bed of the four-way valve (2), the outlet of the power unit (3) is connected to the power unit port (P) of the four-way valve (2), and the inlet of the power unit (3) is connected to the heat exchange circulation port (E) of the four-way valve (2). The four-way valve (2) is equipped with a movable cover slider (21). By moving the cover slider (21), the flow path connection state in the system can be changed, thereby allowing the system to switch between the heat storage mode and the heat release mode.

2. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 1, characterized in that, The power unit interface (P) is located on the first side of the four-way valve (2); the bottom interface (B), the heat exchange circulation interface (E), and the top interface (T) of the packed bed are located on the second side of the four-way valve (2) and are arranged in order from left to right.

3. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 2, characterized in that, The four-way valve (2) is an electromagnetically driven four-way directional valve.

4. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 3, characterized in that, When the four-way valve (2) is de-energized, the cover slider (21) moves to the left under the action of the spring (22), covering the bottom interface (B) of the packed bed and the heat exchange circulation interface (E), so that the flow path from the power unit interface (P) to the top interface (T) of the packed bed and the flow path from the bottom interface (B) of the packed bed to the heat exchange circulation interface (E) are connected, and the system enters the heat storage mode.

5. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 4, characterized in that, In the heat storage mode, the flow path of the heat transfer fluid is as follows: Bottom port of packed bed (1) → Bottom interface of packed bed (B) → Heat exchange circulation interface (E) → Inlet of power unit (3) → Outlet of power unit (3) → Power unit interface (P) → Top interface of packed bed (T) → Cold end heat exchanger (5) → Heater (4) → Top port of packed bed (1) → Bottom port of packed bed (1) to complete the cycle; In the heat storage mode, the inclined temperature layer moves from top to bottom within the packed bed (1).

6. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 5, characterized in that, In the heat storage mode, the heater (4) heats the heat transfer fluid, the user side of the cold end heat exchanger (5) has no working fluid, and the cold end heat exchanger (5) does not exchange heat.

7. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 3, characterized in that, When the four-way valve (2) is energized, the cover slider (21) moves to the right under the action of electromagnetic force, covering the heat exchange circulation interface (E) and the top interface (T) of the packed bed, so that the flow path from the power unit interface (P) to the bottom interface (B) of the packed bed and the flow path from the top interface (T) of the packed bed to the heat exchange circulation interface (E) are connected, and the system enters the heat release mode.

8. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 7, characterized in that, In the heat release mode, the flow path of the heat transfer fluid is as follows: The power unit (3) outlet → power unit interface (P) → bottom interface (B) of the packed bed → bottom port of the packed bed (1) → top port of the packed bed (1) → heater (4) → cold end heat exchanger (5) → top interface (T) of the packed bed → heat exchange circulation interface (E) → inlet of the power unit (3) → outlet of the power unit (3) to complete the cycle; In the heat release mode, the inclined temperature layer moves from bottom to top within the packed bed (1).

9. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to claim 8, characterized in that, In the heat release mode, the heater (4) does not heat the heat transfer fluid, and the cold end heat exchanger (5) transfers heat to the user-side working fluid.

10. The single-tank packed bed thermal storage system based on four-way valve reversing and heat replenishment according to any one of claims 1-9, characterized in that, The heater (4) is also used to provide auxiliary heating to the heat transfer fluid that is about to enter the cold end heat exchanger (5) and whose temperature has been reduced to a preset threshold at the end of the operation of the heat release mode.

Images